ECM Power Source Circuit [11/2021 - ]: Procedure

1. Turn the ignition switch to OFF.
2. Remove the EFI MAIN relay.
3. Check the EFI MAIN relay.

   Refer to PROCEDURE - Step 1

   Is the check result OK?

   Result	Proceed to
   Yes	A
   No (Replace the EFI MAIN relay.)	B

Result: 

B 

REPLACE EFI MAIN RELAY 

Result: 

A 

See step  2

1. Disconnect the connector from ECM.
2. Measure the resistance of harness between ECM connector and engine ground.

   Connector & terminal

   A5-69 (GNDEG3) - Engine ground

   A5-70 (GNDEG4) - Engine ground

   A5-71 (GNDEG1) - Engine ground

   A5-72 (GNDEG2) - Engine ground

   Is the resistance less than 5 Ω?

   Result	Proceed to
   Yes	A
   No (Repair the following item.) Open circuit of harness between ECM connector and engine ground Poor contact of coupling connector	B

Result: 

B 

REPAIR RELATED PARTS 

• Open circuit of harness between ECM connector and engine ground
• Poor contact of coupling connector

Result: 

A 

See step  3

1. Turn the ignition switch to ON.
2. Measure the voltage between ECM connector and engine ground.

   Connector & terminal

   A5-1 (BATT) - Engine ground:

   A5-56 (KEY1) - Engine ground:

   Is the voltage 10 V or higher?

   Result	Proceed to
   Yes	A
   No (Repair the open or ground short in the harness of power supply circuit.)	B

Result: 

B 

REPAIR HARNESS OR CONNECTOR 

Result: 

A 

See step  4

1. Measure the voltage between No. 1 engine room relay block and No. 1 junction block assembly (EFI MAIN relay) terminal and engine ground.

   Connector & terminal

   1 (EFI MAIN relay) - Engine ground:

   5 (EFI MAIN relay) - Engine ground:

   Is the voltage 10 V or higher?

   Result	Proceed to
   Yes	A
   No (Repair the open or ground short in the harness of power supply circuit.)	B

Result: 

B 

REPAIR HARNESS OR CONNECTOR 

Result: 

A 

See step  5

1. Turn the ignition switch to OFF.
2. Install the EFI MAIN relay.
3. Measure the voltage between ECM connector and engine ground.

   Connector & terminal

   A5-12 (SSHUT) - Engine ground:

   Is the voltage 10 V or higher?

   Result	Proceed to
   Yes	A
   No (Repair the open circuit of harness between ECM connector and No. 1 engine room relay block and No. 1 junction block assembly (EFI MAIN relay) terminal.)	B

Result: 

B 

REPAIR HARNESS OR CONNECTOR 

Result: 

A 

See step  6

1. Check for poor contact of ECM connector and No. 1 engine room relay block and No. 1 junction block assembly (EFI MAIN relay).

   Is there poor contact of ECM connector and No. 1 engine room relay block and No. 1 junction block assembly (EFI MAIN relay)?

   Result	Proceed to
   Yes (Repair the following item.) Poor contact of ECM connector Poor contact of No. 1 engine room relay block and No. 1 junction block assembly (EFI MAIN relay).	A
   No	B

Result: 

A 

REPAIR RELATED PARTS 

• Open circuit of harness between ECM connector and No. 1 engine room relay block and No. 1 junction block assembly (EFI MAIN relay)
• Poor contact of No. 1 engine room relay block and No. 1 junction block assembly (EFI MAIN relay)
• Blown out of fuse
• Poor contact of ECM connector

Result: 

B 

See step  7

1. Measure the resistance of harness between ECM connector and No. 1 engine room relay block and No. 1 junction block assembly (EFI MAIN relay) terminal No. 3.

   Connector & terminal

   3 (EFI MAIN relay) - A5-67 (VBEC1)

   3 (EFI MAIN relay) - A5-68 (VBEC2)

   Is the resistance less than 1 Ω?

   Result	Proceed to
   Yes (Check the starter signal circuit.)	A
   No (Repair the following item.) Open circuit of harness between ECM connector and No. 1 engine room relay block and No. 1 junction block assembly (EFI MAIN relay) Blown out of fuse	B

Result: 

A 

CHECK STARTER SIGNAL CIRCUIT. Refer to  Starter Signal Circuit [11/2021 - ]  

Result: 

B 

REPAIR RELATED PARTS 

• Open circuit of harness between ECM connector and No. 1 engine room relay block and No. 1 junction block assembly (EFI MAIN relay)
• Blown out of fuse